Method for making corrugated slabs



July 14, 1953 c, HERZOG 2,645,269

METHOD FOR MAKING CORRUGATED SLABS Filed June 22, 1950 Patented July 14, 1953 METHOD FOR MAKING CORRUGATED SLABS Carl Herzog, Niederurnen, Glarus, Switzerland, assignor to Eternit A.-G., Niederurnen, Glarus,

Switzerland Application June 22, 1950, Serial No. 169,721

In Switzerland June 29, 1949 1 Claims. 1

The most usual method of manufacturing corrugated asbestos-cement slabs is that the ashestos-cement slabs, after having been made on a circular moulding machine, are laid into suitable corrugated moulds while still in the soft, unset state, and they remain in these moulds until sulficiently hardened. These corrugated slabs have the'same thickness of material over all, which is a drawback in so far that, at the overlapping positions, they do not lie snugly against each other, but have free spaces at the tops and bottoms of the corrugations through which driven snow, dust, etc., may enter.

It is also impossible to press these slabs stacked in piles, as is done in the case of flat asbestoscement slabs, since in consequence of the abovementioned free spaces such distortions would oc-- cur in the'corrugated slabs as to render them useless. In addition, the radii of the corrugations of corrugated slabs pressed in this manner would'vary from one corrugated slab to another.

Methods are known according to which corrugated asbestos-cement slabs are moulded from a thick asbestos-cement paste, the corrugated slabs having a greater thickness of material at the tops and bottoms of the corrugations than on the flanks. In this way exact fitting of the corrugations into each other is obtained, but these methods have the drawback that the good felting of the asbestos fibres, such as occurs with the circular moulding machine, is not then obtained, and in consequence the strengths of the material are less. What has been said above holds good, of course, not only for corrugated slabs of asbestos-cement, but also for corrugated slabs consisting of other materials for instance those consisting of organic or inorganic fibres and a binding means.

In the method according to the present invention, the afore-mentioned drawbacks are avoided in that, additional material-for instance, asbestos cement-is brought onto the tops and bottoms of the corrugations of unset corrugated slabs which are of a uniform thickness of material over all, and afterwards a plurality of such corrugated slabs filed on top of each other, are subjected to pressing.

The invention relates further to an appliance for carrying out the foregoing method, the appliance having conveying means for the corrugated slabs of uniform thickness and also coating elements for applying additional material only to the tops and bottoms of the corrugations.

The invention will now be explained more precisely with reference to the accompanying drawing. Here the explanation is with regard to corrugated slabs made of asbestos cement, but the corrugated slabs could of course. consist of some other of the above-mentioned materials. In the drawing:

Fig. 1 shows a partial cross-section through two corrugated slabs of uniform thickness lying on each other,

Fig. 2 a corresponding cross-section through corrugated slabs manufactured according to the new method, and

Figs. 3 and 4 illustrate diagrammatically an appliance for carrying out the new method, viewed from the front and from the side.

Fig. 1 shows unpressed corrugated slabs of known execution, where the free spaces are at once visible which occur when adjacent corrugated slabs are laid over each other, into which spaces driven snow, dust, etc. may penetrate. These free spaces also make it impossible to press these corrugated slabs stacked in piles, although pressing is really desirable in order to obtain a close-fitting and therefore resistant jointing of the slabs. V

Fig. 2 now shows that these free spaces l are no longer present in the case of corrugated slabs in which the thickness of material at the tops and bottoms of the corrugations is greater than on the flanks. Besides that, it is possible to press such corrugated slabs and thus render their texture more dense.

The method of manufacturing such corrugated slabs according to the invention will now be described with reference to the diagrammatic Figs. 3 and 4. On a suitable corrugated base sheet 2, an asbestos-cement web 3 which has not yet set is placed by suitable conveying means (not illustrated in the drawing). Due to its wet con.- dition, the web 3 assumes the shape of the base sheet 2, as shown. The web and sheet assembly 2, 3 is then moved along in the direction of the corrugations below a delivery device which as a whole is designated with the numeral 4. This delivery device sprinkles the bottoms and tops of the corrugations with a uniform layer of asbestos cement, whilst the flanks between the tops and bottoms of the corrugations are not sprinkled. As delivery device in the form of execution illustrated, revolving screens or drums 5 are provided which are rotatably supported and provided with perforations at positions 5 situated certain distances apart from each other. These positions 6 are arranged in such a way that asbestos cement can only fall onto the tops and thickness so that, with the later pressing, a form" of slab is obtained which ensures the corrugated slabs fitting well together. The asbestos cement may be applied in a dry or moistened state. A plurality of these sprinkled web and corrugated sheet assemblies are then piled on each other and pressed in a known manner, a suitably profiled matrixlbeing set on the press table and alsoon the press head, in order to prevent distortion of the corrugated moulding plates. 7

What I claim is:

In' a process of manufacturing corrugated slabs, particularly from an asbestos-cement mixture, the steps of placing a wet web of the mixture of substantially uniform thickness on a rigid corrugated sheet so as to cause said web to conform to the shape of said corrugated sheet, sprinkling additional quantities of the mixture along the tops and bottoms of the corrugations of said web, placing a plurality of said sprinkled web and rigid sheet'asse'mblies on top of each other to form a pile in which said sprinkled webs and rigid sheets alternate, and applying pressure to said pile,

CARL HERZOG.

References Cited in the file of this patent UNITED STATES PATENTS 

